The Diversity and Nitrogen Metabolism of Culturable Nitrate-Utilizing Bacteria Within the Oxygen Minimum Zone of the Changjiang (Yangtze River) Estuary

Abstract

The nitrogen cycle is an indispensable part of the biogeochemical cycle, and the reactions that occur in the ocean oxygen minimum zone (OMZ) mediate much of the loss of nitrogen from oceans worldwide. Here, nitrate-utilizing bacteria were isolated from the water column at 17 stations within the OMZ of the Changjiang (Yangtze River) Estuary using selective media and a culture-dependent method. The microbial diversity, nitrogen metabolism and nitrate reduction test of culturable heterotrophic bacteria were examined. A total of 164 isolates were obtained; they were mostly affiliated with Proteobacteria (81.1%), Actinobacteria (5.5%), Bacteroidetes (12.3%), and Firmicutes (0.6%). Pseudomonas aeruginosa, Sphingobium naphthae, and Zunongwangia profunda were found at most stations. Among 24 tested representative strains, 8 were positive for nitrate reduction; they belonged to genera Aurantimonas, Halomonas, Marinobacter, Pseudomonas, Thalassospira, and Vibrio. Pseudomonas aeruginosa contained the genes (napAB, norBC, nirS, and nosZ) for complete denitrification and may be responsible for mediating denitrification. 66% representative isolates (16/24) contained genes for reducing nitrate to nitrite (nasA, napAB, or narGHI) and 79% representative isolates (19/24) possessed genes for converting nitrite to ammonia (nirA or nirBD), suggesting that nitrate and nitrite could act as electron acceptors to generate ammonium, subsequently being utilized as a reduced nitrogen source. This study improves our understanding of the microbial diversity within the OMZ of Changjiang Estuary and may facilitate the cultivation and exploitation of bacteria involved in the nitrogen cycle.

Interactive Effects of Biochar and Nitrogen Fertilizer on Plant Performance Mediated by Soil Microbial Community in a Eucalypt Plantation

“…The significant influence of soil atom % 15 N on dominant soil bacteria in our study suggests that the application of fertilizer has the potential to regulate soil bacterial composition on the phylum level by changing the N content in soils. The positive correlations between Proteobacteria taxa and soil NH 4 + suggest that soil NH 4 + is the preferred inorganic N form for these selected bacterial phyla [55][56][57]. The negative correlations between Proteobacteria taxa and soil TN agree with other reports [2,58].…”

Isolation and screening of indigenous nitrifying bacteria to enhance nutrient recovery in an aquaponics system

“…Another study reported that M. nauticus isolated from water of an oil field in Vietnam was able to grow in wide ranges of temperatures (13°C–50°C) and salinity (0–20% NaCl) (Huu et al, 1999), therefore consider as a halotolerant bacterium (Tourova et al, 2022). Additionally, M. nauticus have been documented to carry genes involved in denitrification pathways ( nirS , norBC , and nosZ ) in which nitrate is reduced to molecular nitrogens (He et al, 2021; Jiang et al, 2023). However, no study, to the authors' knowledge, has reported specifically that M. nauticus is able to degrade ammonia; therefore the present study is the first study to report the capacity of M. nauticus to degrade ammonia.…”